Just wanted to make another comment on another avenue of why a ferret
wheezes. I had a beautiful little ferret named Tinder who did not wheeze
when we got her, but noticed about two years later that she wheezed and
snored in her sleep. At first is was cute and sweet, and it made it easy
for us to find her as all of our ferrets are free roamers. But about a
month after it started, we noticed that it was getting louder and it
gave us concern. We gave her a thorough check and found a lump under her
throat. An x-ray revealed a mass was pushing her trachea up and over to
the left causing her to have her airway partially blocked. Tinder was
always a thin ferret, but after surgery, she began to fatten up.

It is unlikely that this is the problem with Squeak, but I just wanted
to make others aware that sometimes wheezing could be something else.